In vitro effect of bethanechol and suberyldicholine on regions of guinea pig esophagus

Effects of Microbeam Irradiation on Rodent Esophageal Smooth Muscle Contraction

BACKGROUND

High-dose-rate radiotherapy has shown promising results with respect to normal tissue preservation. We developed an ex vivo model to study the physiological effects of experimental radiotherapy in the rodent esophageal smooth muscle.

METHODS

We assessed the physiological parameters of the esophageal function in ex vivo preparations of the proximal, middle, and distal segments in the organ bath. High-dose-rate synchrotron irradiation was conducted using both the microbeam irradiation (MBI) technique with peak doses greater than 200 Gy and broadbeam irradiation (BBI) with doses ranging between 3.5-4 Gy.

RESULTS

Neither MBI nor BBI affected the function of the contractile apparatus. While peak latency and maximal force change were not affected in the BBI group, and no changes were seen in the proximal esophagus segments after MBI, a significant increase in peak latency and a decrease in maximal force change was observed in the middle and distal esophageal segments.

CONCLUSION

No severe changes in physiological parameters of esophageal contraction were determined after high-dose-rate radiotherapy in our model, but our results indicate a delayed esophageal function. From the clinical perspective, the observed increase in peak latency and decreased maximal force change may indicate delayed esophageal transit.

Esophagus stretch tests: Biomechanics for tissue engineering and possible implications on the outcome of esophageal atresia repairs performed under excessive tension

BACKGROUND

Esophageal biomechanical studies are important to understand structural changes resulting from stretches during repair of esophageal atresias as well as to obtain values to compare with the biomechanics of tissue-engineered esophagus in the future. This study aimed to investigate light microscopic changes after uniaxial stretching of the ovine esophagus.

METHODS

In vitro uniaxial stretching was performed on esophagi (n = 20) of 1-month-old lambs within 4-6 h post-mortem. Esophagi were divided into 5 groups: control and stretched (1.1, 1.2, 1.3 and 1.4). Force and lengthening were measured with 5 cycles performed on every specimen using a PBS organ bath at 37 °C. Histological studies were performed on the 5 groups.

RESULTS

Low forces of ~ 2 N (N) were sufficient for a 1.2-1.25 stretch in the 1st cycle, whereas a three times higher force (~ 6 N) was needed for a stretch of 1.3. In the 2nd to 5th cycle, the tissue weakened and a force of ~ 3 N was sufficient for a stretch of 1.3. Histologically, in the 1.3-1.4 stretch groups, rupture of muscle fibers and capillaries were observed, respectively. Changes in mucosa and collagen fibers could not be observed.

CONCLUSIONS

These results offer norm values from the native esophagus to compare with the biomechanics of future tissue-engineered esophagus. Esophageal stretching > 1.3 leads to tears in muscle fibers and to rupture of capillaries. These findings can explain the decrease in microcirculation and scarring in mobilized tissue and possibly offer clues to impaired motility in esophagus atresias repaired under excessive tension.

Effects of sodium hydroxide exposure on esophageal epithelial cells in an in vitro ovine model: implications for esophagus tissue engineering

BACKGROUND

Esophagus tissue engineering holds promises for esophageal replacement after severe caustic injuries. The aim of this study was to determine whether viable esophageal epithelial cells could be isolated from an esophagus exposed to varying concentrations of alkali with regard to number, viability, and morphology during in vitro culture.

METHODS

Ovine esophagi were exposed to phosphate-buffered saline 2.5%, 15%, or 25% sodium hydroxide (NaOH). The effect of NaOH concentrations on epithelial damage was assessed histologically. Esophageal epithelial cells were then isolated, and cell count and viability were investigated. Finally, cell number, viability, and morphology of esophageal epithelial cells were determined for 24 days of in vitro culture.

RESULTS

Histologic analysis showed a progressive destruction of the epithelium proportional to increasing NaOH concentrations. Esophagi treated with phosphate-buffered saline and 2.5% NaOH showed significantly higher viable cell counts after isolation and culture in comparison with those treated with 15% to 5% NaOH.

CONCLUSION

The evidence presented in this study indicates that epithelial biopsies from an esophagus exposed to low concentrations (2.5%) of NaOH will still yield large numbers of viable cells suitable for tissue engineering applications. In cases of exposure to higher concentrations (15%-25%), alternative cell sources for epithelial regeneration, such as stem cells, will be necessary for tissue engineering applications.